非生物胁迫诱导的GmMYB基因克隆与表达分析

本研究室根据一段抗逆的EST序列,从栽培大豆东农42中克隆到4个开放阅读框均是外显子和内含子间隔构成的R2R3-MYB基因,其中Gm02g01300、Gm03g38040和Gm10g01340与已公布的Williams82基因组序列完全一致,Gm19g40650第375位的单核苷酸突变导致多肽链第125位的氨基酸发生置换(GAG375→GAC375,E125→D125)。以人工气候箱内模拟非生物胁迫(盐、碱、干旱和低温)处理栽培大豆东农42芽期,选择适宜时间点,采用荧光定量PCR技术,检测R2R3-MYB基因的表达。结果表明,4个基因的表达水平都存在明显波动,呈诱导后短暂上调或下调两种表达模式,但表达时间、强度和趋势存在明显差异;Gm02g01300受干旱诱导明显,Gm03g38040受多种胁迫条件诱导表达强烈,推测这些基因在大豆非生物胁迫的调控中起到重要作用;另外,在子叶与胚间,单个基因的表达也存在差异;多种非生物胁迫条件下,基因的表达不仅存在时空差异,可能也具有调控模式的差异。

Water Management for Improvement of Rice Yield,Appearance Quality and Palatability with High Temperature During Ripening Period

To clarify the optimal water management in large-scale fields under high temperatures at the ripening period,effective water managements during this period for improvement of yield,appearance quality and palatability were investigated.Compared with intermittent irrigation and flooded irrigation,the soil temperature with saturated irrigation remained low throughout the day,and the decrease rate of the bleeding rate of hills was the lowest.These results suggested that the saturated irrigation maintained root activity.For the three irrigation types,the number of spikelets per m2 and 1000-grain weight were similar,however,saturated irrigation resulted in significantly higher rice yield due to improvement in the percentage of ripened grains.The saturated irrigation produced a high percentage of perfect rice grains and thicker brown rice grain,furthermore,the palatability of cooked rice was excellent because protein content and hardness/adhesion ratio were both low.Thus,under high-temperature ripening conditions,soil temperature was lowered and root activity was maintained when applying saturated irrigation after heading time.The results indicated that saturated irrigation is an effective countermeasure against high-temperature ripening damage.

Identification of additional QTLs for flowering time by removing the effect of the maturity gene E1 in soybean

The adaptability of soybean to be grown at a wide range of latitudes is attributed to natural variation in the major genes and quantitative trait loci （QTLs） that control flowering time and maturity. Thus, the identification of genes controlling flowering time and maturity and the understanding of their molecular basis are critical for improving soybean productivity. However, due to the great effect of the major maturity gene E1 on flowering time, it is difficult to detect other small-effect QTLs. In this study, aiming to reduce the effect of the QTL, associated with the E1 gene, on the detection of other QTLs, we divided a population of 96 recombinant inbred lines （RILs） into two sub-populations： one with the E1 allele and another with the elns allele. Compared with the results of using all 96 recombinant inbred lines, additional QTLs for flowering time were identified in the sub-populations, two （qFT-B1 and qFT-H） in RILs with the E1 allele and one （qFT-J-2） in the RILs with the elnl allele, respectively. The three QTLs, qFT-B1, qFT-H and qFT-J-2 were true QTLs and played an important role in the regulation of growth period. Our data provides valuable information for the genetic mapping and gene cloning of traits controlling flowering time and maturity and will help a better understanding of the mechanism of photoperiod-regulated flowering and molecular breeding in soybean.

Distribution and Quantity of Root Systems of Field-Grown Erianthus and Napier Grass

Cellulosic bioethanol produced from non-edible plants reduces potential food-fuel competition and, as such, is receiving increasing attention. In the raw material production of cellulosic bioethanol, the aboveground biomass of plants is entirely harvested;consequently, the plant roots represent the major source of organic matter incorporated into the soil. We selected Erianthus and Napier grass as the raw materials for cultivation in Asia. However, information about whether these 2 species provide sufficient root volume to sustain soil fertility is limited. Therefore, we examined the spatial distribution of the roots of these 2 plants, and quantified root mass and length. Erianthus and Napier grass were either grown in fields or greenhouses in Tokyo (Japan) and Lampung (Indonesia), and then their roots were exposed from adjacent soil profiles. Both species developed large, deep roots, penetrating 2.0-2.6 m deep into the soil. Root depth indexes showed that the roots of both species penetrated much deeper into the soil compared to monocot crop species, being more comparable to dicot species. Erianthus developed a root mass and length of 384-850 g·m-2 and 28.8-35.8 km·m-2, while the values for Napier grass were 183-448 g·m-2 and 15.6-43.6 km·m-2, respectively. These values exceeded the maximum values previously recorded for common crop species. Our study confirmed that Erianthus and Napier grass develop deep root systems, with substantially large biomass;hence, we suggest that both plants supply root biomass in large quantities, representing possible major sources of soil organic matter.

Root Anatomical Structure of <i>Jatropha curcas</i>Seedlings—A Short Report

Jatropha curcas has been expected as a biodiesel plant which can be grown in degraded lands. The structure of roots at the seedling stage, in particular cell wall modification in exodermis and endodermis, was microscopically observed. In addition, it was discussed if the first four peripheral roots that emerge from the base of the primary root (taproot) are lateral roots or adventitious roots. The primary root and the first-order lateral roots formed diarchy stele, in which two protoxylem poles present in primary xylem of root. Consequently, the first four peripheral roots cannot be lateral roots, but should be adventitious roots formed at the base of hypocotyl. In both the primary and first-order lateral roots, exodermis and endodermis formed highly lignified cell walls. Moreover, the exodermal and endodermal cell walls formed Casparian strips, which could be observed without special staining by fluorescent dye under ultraviolet microscopy. Such cell-wall modification in root exodermis and endodermis may play an important role for J. curcas under soil stresses in degraded lands.

Silicon Deposition in Leaf Trichomes of Cucurbitaceae Horticultural Plants: A Short Report

Silicon deposition in leaf trichome of six horticultural Cucurbitaceae species, cucumber (Cucumis sativus), pumpkin (Cucurbita maxima), melon (Cucumis melo), watermelon (Citrullus lanatus), sponge gourd (Luffa cylindrica) and bottle gourd (Lagenaria siceraria var. hispida) was observed by an X-ray microanalyzer coupled with an environmental scanning electron microscope. The elements that presented in the surface of three or four leaves of the individual species were detected and mapped by the X-ray microanalyzer. In leaves of cucumber, pumpkin, and melon, high accumulation of silicon was detected in cells surrounding the bases of the trichome hair and the hair itself deposited calcium. On the other hand, in sponge gourd and bottle gourd, high accumulation of silicon was detected only in the hair. In watermelon leaves, silicon deposited both in the hair and in cells surrounding the bases of the hair. Thus, horticultural Cucurbitaceae plants have interspecific variation in the pattern of silicon deposition in leaf trichomes.

Root Morphology and Anatomy of Field-Grown Erianthus arundinaceus

Erianthus species are perennial C4 grasses with such high biomass productivity and high tolerance to environmental stresses that they can be grown in marginal land to supply raw material for cellulosic bioethanol. Because high biomass production and strong tolerance to environmental stresses might be based on their large and deep-root system, we closely examined the morphology and anatomy of roots in first-year seedlings of field-grown Erianthus arundinaceus. The deep-root system of E. arundinaceus consists of many nodal roots growing with steep growth angles. Diameter of nodal roots with large variations (0.5 - 5 mm) correlates with the size and number of large xylem vessels. The microscopic observation shows that the nodal roots with dense root hairs developed soil sheath, hypodermis with lignified sclerenchyma in the outer cortex, and aerenchyma in the mid-cortex. In addition, starch grains were densely accumulated in the stele of nodal roots in winter. In the first year, E. arundinaceus developed less lateral roots than other reported grass species. The lateral roots formed a large xylem vessel in the center of the stele and no hypodermis in the outer cortex. Morphology and anatomy of E. arundinaceus root were discussed with reference to strong tolerance to environmental stresses.

Cultivation of <i>Erianthus</i>and Napier Grass at an Abandoned Mine in Lampung, Indonesia

The production of cellulosic bioethanol from non-edible plants is drawing increasing attention, as it potentially avoids food-fuel competition. Because growing such plants on farmland indirectly reduces food availability, the plants should be grown on marginal, non-arable lands. In this study, we evaluated the growth of cellulosic energy crops at a former mining site in Indonesia. This mine was abandoned because it contained few mineral deposits, and exposed subsoils rather than toxic soils prevented revegetation. In the first trial, growths of two energy plant species Erianthus spp. and Napier grass (Pennisetum purpureum) were compared with that of maize (Zea mays) at the mine site and a nearby degraded farm. Erianthus and Napier grass produced 11.7 and 22.5 t·ha-1 of shoot dry matter at 8 months after planting (MAP) in the farm respectively while maize plants failed to establish, but none of the three species grew at the mine. In the second trial, two-week-old seedlings of Erianthus and Napier grass rather than stem cuttings as used in the first trial were planted at the mine site. Erianthus and Napier grass produced 16.3 and 24.0 t·ha-1 of shoot dry matter over the course of 18 months, respectively. Application of organic fertilizer significantly increased shoot dry matter to 18.9 and 39.6 t·ha-1 in Erianthus and Napier grass, respectively. During the 18-month growth period, both of the energy plants significantly increased soil carbon at the 0 - 0.3 m depth from 0.33% to 1.15% - 1.23% when chemical fertilizer was applied and to 0.67% - 0.69% when both chemical and organic fertilizers were applied. From 0 - 5 MAP, soil surface level dropped by 28.0 - 34.7 mm in plots without plants due to soil erosion. In contrast, both of the energy plants significantly reduced the drop of soil surface level to 16.0 - 19.3 mm in plots with chemical fertilizer alone and to 18.0 - 20.7 mm in plots with chemical and organic fertilizers. Proportions of small soil particles, that would be easily detached and transported by water flow compared with large particles, were larger in the planted plots than the no-plant plots at 16 MAP. The results suggest that successful cultivation of energy plants on abandoned mine sites is possible, particularly if seedlings are transplanted and the crops are fertilized with organic fertilizer. In addition, the cultivation of Erianthus and Napier grass has positive impacts on soil quality that may contribute to their sustainability as crops and to the conservation of the local ecosystem.

Molecular mechanisms for the photoperiodic regulation of flowering in soybean

Photoperiodic flowering is one of the most important factors affecting regional adaptation and yield in soybean(Glycine max). Plant adaptation to long-day conditions at higher latitudes requires early flowering and a reduction or loss of photoperiod sensitivity;adaptation to short-day conditions at lower latitudes involves delayed flowering, which prolongs vegetative growth for maximum yield potential. Due to the influence of numerous major loci and quantitative trait loci(QTLs), soybean has broad adaptability across latitudes. Forward genetic approaches have uncovered the molecular basis for several of these major maturity genes and QTLs. Moreover, the molecular characterization of orthologs of Arabidopsis thaliana flowering genes has enriched our understanding of the photoperiodic flowering pathway in soybean. Building on early insights into the importance of the photoreceptor phytochrome A, several circadian clock components have been integrated into the genetic network controlling flowering in soybean: E1, a repressor of FLOWERING LOCUS T orthologs, plays a central role in this network. Here, we provide an overview of recent progress in elucidating photoperiodic flowering in soybean, how it contributes to our fundamental understanding of flowering time control, and how this information could be used for molecular design and breeding of high-yielding soybean cultivars.

FT5a interferes with the Dt1-AP1 feedback loop to control flowering time and shoot determinacy in soybean

Flowering time and stem growth habit determine inflorescence architecture in soybean, which in turn influences seed yield. Dt1, a homolog of Arabidopsis TERMINAL FLOWER 1(TFL1), is a major controller of stem growth habit, but its underlying molecular mechanisms remain unclear.Here, we demonstrate that Dt1 affects node number and plant height, as well as flowering time,in soybean under long-day conditions. The b ZIP transcription factor FDc1 physically interacts with Dt1, and the FDc1-Dt1 complex directly represses the expression of APETALA1(AP1). We propose that FT5 a inhibits Dt1 activity via a competitive interaction with FDc1 and directly upregulates AP1. Moreover, AP1 represses Dt1 expression by directly binding to the Dt1 promoter, suggesting that AP1 and Dt1 form a suppressive regulatory feedback loop to determine the fate of the shoot apical meristem. These findings provide novel insights into the roles of Dt1 and FT5 a in controlling the stem growth habit and flowering time in soybean, which determine the adaptability and grain yield of this important crop.

Identifying potential field sites for production of cellulosic energy plants in Asia

Cellulosic bioethanol produced from non-edible plants avoids food-fuel competition.Growing such plants on marginal non-arable lands also avoids the use of farmland.In this study,attempts were made to identify potential field sites for cellulosic bioethanol production in Asia.In this study,GIS databases containing information about requirements such as land use,landform,and climate were superimposed.Areas with terrestrial constraints were then removed from the candidate field sites using a terrain slope database.The remaining lands were evaluated using a net primary production(NPP)database.Of these areas,southern and eastern India,northeastern Thailand,and southern Sumatra(Indonesia)had high NPP.In the 2nd phase,local information regarding infrastructure,and agriculture were analyzed.Field-establishment feasibility was high for eastern India and southern Sumatra.Potential field sites were then located in satellite images of these two areas.In the 3rd phase,soils around potential sites were evaluated.Local residents were interviewed to estimate the cost of producing plants for biomass energy.Sites selected using this simple method are suitable for biomass production.

Current overview on the genetic basis of key genes involved in soybean domestication

Modern crops were created through the domestication and genetic introgression of wild relatives and adaptive differentiation in new environments.Identifying the domestication-related genes and unveiling their molecular diversity provide clues for understanding how the domesticated variants were selected by ancient people,elucidating how and where these crops were domesticated.Molecular genetics and genomics have explored some domestication-related genes in soybean(Glycine max).Here,we summarize recent studies about the quantitative trait locus(QTL)and genes involved in the domestication traits,introduce the functions of these genes,clarify which alleles of domesticated genes were selected during domestication.A deeper understanding of soybean domestication could help to break the bottleneck of modern breeding by highlighting unused genetic diversity not selected in the original domestication process,as well as highlighting promising new avenues for the identification and research of important agronomic traits among different crop species.

Correction:Current overview on the genetic basis of key genes involved in soybean domestication

Correction:aBIOTECH(2022)3:126–139 https://doi.org/10.1007/s42994-022-00074-5 The article‘‘Current overview on the genetic basis of key genes involved in soybean domestication’’,written by Sijia Lu,Chao Fang,Jun Abe,Fanjiang Kong and Baohui Liu,was originally published Online First without Open Access.After publication in volume 3,issue 2,pages 126–139 the authors decided to opt for Open Choice and to make the article an Open Access publication.Therefore,the copyright of the article has been changed to The Authors 2024 and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License,which permits use,sharing,adaptation,distribution and reproduction in any medium or format,as long as you give appropriate credit to the original author(s)and the source,provide a link to the Creative Commons licence,and indicate if changes were made.