Physiological and Biochemical Characteristics and Response Patterns of Salinity Stress Responsive Genes (SSRGs) in Wild Quinoa (Chenopodium quinoa L.)

Cultivating salt-tolerant crops is a feasible way to effectively utilize saline-alkali land and solve the problem of underutilization of saline soils.Quinoa,a protein-comprehensive cereal in the plant kingdom,is an exceptional crop in terms of salt stress tolerance level.It seems an excellent model for the exploration of salt-tolerance mechanisms and cultivation of salt-tolerant germplasms.In this study,the seeds and seedlings of the quinoa cultivar Shelly were treated with different concentrations of NaCl solution.The physiological,biochemical characteristics and agronomic traits were investigated,and the response patterns of three salt stress-responsive genes(SSRGs)in quinoa were determined by real-time PCR.The optimum level of stress tolerance of quinoa cultivar Shelly was found in the range of 250–350 mM concentration of NaCl.Salt stress significantly induced expression of superoxide dismutase(SOD),peroxidase(POD),and particularly betaine aldehyde dehydrogenase(BADH).BADH was discovered to be more sensitive to salt stress and played an important role in the salt stress tolerance of quinoa seedlings,particularly at high NaCl concentrations,as it displayed upregulation until 24 h under 100 mM salt treatment.Moreover,it showed upregulation until 12 h under 250 mM salt stress.Taken together,these results suggest that BADH played an essential role in the salt-tolerance mechanism of quinoa.Based on the expression level and prompt response induced by NaCl,we suggest that the BADH can be considered as a molecular marker for screening salt-tolerant quinoa germplasm at the early stages of crop development.Salt treatment at different plant ontogeny or at different concentrations had a significant impact on quinoa growth.Therefore,an appropriate treatment approach needs to be chosen rationally in the process of screening salt-tolerant quinoa germplasm,which is useful to the utilization of saline soils.Our study provides a fundamental information to deepen knowledge of the salt tolerance mechanism of quinoa for the development of salt-tolerant germplasm in crop breeding programs.

Cadmium-Induced Structure Change of Pigment Glands and the Reduction of the Gossypol Content in Cottonseed Kernels

The risk of cotton production on arable land contaminated with heavy metals has increased in recent years.Cotton shows stronger and more extensive resistance to heavy metals,such as cadmium(Cd)than that of other major crops.Here,a potted plant experiment was performed to study Cd-induced alterations in the cottonseed kernel gossypol content and pigment gland structure at maturity in two transgenic cotton cultivars(ZD-90 and SGK3)and an upland cotton standard genotype(TM-1).The results showed that Cd accumulation in cottonseed kernels increased with increasing Cd levels in the soil.The seed kernel Cd content in plants grown on Cd-treated soils was 10-20 times greater than the amount in the corresponding controls.There was a significant difference in Cd accumulation in cottonseed kernels at the 400 and 600μM Cd levels.Cd accumulation was higher in SGK3 and ZD-90 than in TM-1.However,the gossypol content in cottonseed kernels was lower in SGK3 and ZD-90 than in TM-1.There was a negative correlation(r=0.550)between Cd accumulation and the gossypol content in cottonseed kernels.The density of cottonseed kernel pigment glands decreased under Cd stress.This is consistent with the change in gossypol content,which decreased under Cd stress.The damage of the cultivars ZD-90 and SGK3 from Cd poisoning was relatively low under Cd stress,while TM-1 was seriously affected and exhibited Cd sensitivity.Further studies are necessary to understand the cause of the reduced gossypol content in cotton seeds under Cd stress.

A reference-grade genome assembly for Gossypium bickii and insights into its genome evolution and formation of pigment glands and gossypol

The pigment gland is a morphological characteristic of Gossypium and its related genera.Gossypium bickii(G_(1))is characterized by delayed pigment gland morphogenesis in the cotyledons.In this study,a referencegrade genome of G_(1) was generated,and comparative genomics analysis showed that G_(1) was closest to Gossypium australe(G_(2)),followed by A-and D-genome species.Two large fragment translocations in chromosomes 5 and 13 were detected between the G genome and other Gossypiumgenomes and were unique to the G_(1) and G_(2) genomes.Compared with the G_(2) genome,two large fragment inversions in chromosomes 12 and 13 were detected in G_(1).According to the phylogeny,divergence time,and similarity analysis of nuclear andchloroplast genomes,G_(1)was formedby hybridization between Gossypium sturtianum(C_(1))and a common ancestor of G_(2) and Gossypiumnelsonii(G_(3)).The coordinated expression patterns of pigment gland formation(GoPGF)and gossypol biosynthesis genes in G_(1) were verified to be consistent with its phenotype,and nine genes thatwere related to theprocessof pigmentgland formationwere identified.Anovel gene,GbiCYP76B6,regulated by GoPGF,was found to affect gossypol biosynthesis.These findings offer insights into the origin and evolution of G_(1) and its mechanism of pigment gland formation and gossypol biosynthesis.

Inheritance of the delayed gland morphogenesis trait in Australian wild species of Gossypium

Five Australian wild cotton species with the delayed gland morphogenesis trait, as well as G. arboreum, G. davidsonii and four different gland genotypes of G. hirsutum, Gl2Gl2Gl3Gl3, Gl2Gl2gl3gl3, gl2gl2Gl3Gl3, and gl2gl2gl3gl3, were used in this experiment and 10 interspecific hybrids were obtained by the crossing among them. According to the gland expression on the seeds and plants of the interspecific hybrids, the inheritance of the delayed gland morphogenesis trait of Australian wild cotton species was opened out as follows: (i) the inheritance of the delayed gland morphogenesis trait was almost the same among the 5 Australian wild cotton species, and the gene or genes which controlled this trait may be located in the same loci. (ii) The glandless seed trait of the Australian wild cotton species was dominant over the glanded seed trait of G. arboreum, a genome A species, and the seeds of interspecific hybrid F1 between them were glandless. However, it was recessive over the glanded character of