Genome-wide identification and functional characterization of the MdCLE peptide family in apple(Malus×domestica)

The CLAVATA3/EMBRYO SURROUNDING REGION-related(CLE)peptides are critical for stem cell homeostasis in plant shoot and root apical meristem.Although CLE genes have been reported in numerous plants,there is limited information for apple.Here,twenty-five MdCLE genes were identified fromapple genome(Apple Genome V1.0 predicted peptides).Analysis of chromosomal location showed that the 25 MdCLE genes were located on 12 of 17 apple chromosomes.Genetic structure analysis showed that 21 of 25 the MdCLE genes were intron-free.Expression patterns showed thatmost of the MdCLE genes showed higher expression levels in leaves and root compared with the other tissues.In addition,expression analysis demonstrated that MdCLE genes had different gene expression patterns for abiotic stress treatment,suggesting their potential roles in acclimation of apple to adverse environments.The 25 MdCLE genes encoded 19 different CLE peptides,and they were divided into two groups depending on their effects on the inhibition of Arabidopsis root growth.Our results suggest that MdCLE genesmay have an important but redundant function in regulating plant growth and development,and this work provides valuable references for further investigation of the biological functions of MdCLE genes.

OsRLR4 binds to the OsAUX1 promoter to negatively regulate primary root development in rice

Root architecture is one of the most important agronomic traits that determines rice crop yield. The primary root(PR) absorbs mineral nutrients and provides mechanical support;however, the molecular mechanisms of PR elongation remain unclear in rice. Here, the two loss-of-function T-DNA insertion mutants of root length regulator 4(Os RLR4), osrlr4-1 and osrlr4-2 with longer PR, and three Os RLR4 overexpression lines, OE-Os RLR4-1/-2/-3 with shorter PR compared to the wild type/Hwayoung(WT/HY), were identified. Os RLR4 isone of five members of the PRAF subfamily of the regulator chromosome condensation1(RCC1) family. Phylogenetic analysis of Os RLR4 from wild and cultivated rice indicated that it is under selective sweeps, suggesting its potential role in domestication. Os RLR4 controls PR development by regulating auxin accumulation in the PR tip and thus the root apical meristem activity. A series of biochemical and genetic analyses demonstrated that Os RLR4 functions directly upstream of the auxin transporter Os AUX1. Moreover, Os RLR4 interacts with the TRITHORAX-like protein Os Trx1 to promote H3 K4 me3 deposition at the Os AUX1 promoter, thus altering its transcription level. This work provides insight into the cooperation of auxin and epigenetic modifications in regulating root architecture and provides a genetic resource for plant architecture breeding.

Receptor-like protein kinases:Key regulators controlling root hair development in Arabidopsis thaliana

Root hairs are tubular outgrowths specifically differentiated from epidermal cells in a differentiation zone. The formation of root hairs greatly increases the surface area of a root and maximizes its ability to absorb water and inorganic nutrients essential for plant growth and development. Root hair development is strictly regulated by intracellular and intercellular signal communications. Cell surface-localized receptor-like protein kinases （P, LKs） have been shown to be important components in these cellular processes, tn this review, the functions of a number of key P, LKs in regulating Arabidopsis root hair development are discussed, especially those involved in root epidermal cell fate determination and root hair tip growth.

An auxin‐responsive endogenous peptide regulates root development in Arabidopsis

Auxin plays critical roles in root formation and development. The components involved in this process, however, are not well understood. Here, we newly identified a peptide encoding gene, auxin-responsive endogenous polypeptide 1 （AREP1）, which is induced by auxin, and mediates root development in Arabidopsis. Expression of AREP1 was specific to the cotyledon and to root and shoot meristem tissues. Amounts of AREP1 transcripts and AREP1-green fluorescent protein fusion proteins were elevated in response to indoleacetic acid treatment. Suppression of AREP1 through RNAi silencing resulted in reduction of primary root length, increase of lateral root number, and expansion of adventitious roots, compared to the observations in wild-type plants in the presence of auxin. By contrast, transgenic plants overexpressing AREP1 showed enhanced growth of the primary root under auxin treatment. Additionally, rootmorphology, including lateral root number and adventitious roots, differed greatly between transgenic and wildtype plants. Further analysis indicated that the expression of auxin-responsive genes, such as IAA3, IAA7, IAA17, GH3.2, GH3.3, and SAUR-AC1, was significantly higher in AREP1 RNAi plants, and was slightly lower in AREP1 overexpressing plants than in wildtype plants. These results suggest that the novel endogenous peptide AREP1 plays an important role in the process of auxinmediated root development.

Acupuncture Principle of Tonifying Qi and Regulating Blood,Supporting the Root and Fostering the Source on Aging and Senile Diseases

Along with the increasing life span, aging and related diseases have become a serious medical and social problem that has roused global attention. In this paper, under the guidance of traditional Chinese medicine （TCM）, the author raises a theory of ＂dysfunction of Sanjiao qi activity＂ based on the studies and discussions of classical literatures on Sanjiao theory by combining knowledge in modern integrative traditional Chinese and Western medicine for aging from his more than 30 years of experiences of clinical and experimental practices. The author also tries to explain the mechanisms for aging from the whole aspect of Sanjiao qi activity.

Poly(ADP-ribose) polymerases regulate cell division and development in Arabidopsis roots

Root organogenesis involves cell division, differentiation and expansion. The molecular mechanisms regulating root development are not fully understood. In this study, we identified poly（adenosine diphosphate （ADP）-ribose） polymerases （PARPs） as new players in root development. PARP catalyzes poly（ADP-ribosyl）ation of proteins by repeatedly adding ADP-ribose units onto proteins using nicotinamide adenine dinucleotide （NAD ） as the donor. We found that inhibition of PARP activities by 3-aminobenzomide （3-AB） increased the growth rates of both primary and lateral roots, leading to a more developed root system. The double mutant of Arabidopsis PARPs, parplparp2, showed more rapid primary and lateral root growth. Cyclin genes regulating G1-to-S and G2-to-M transition were up-regulated upon treatment by 3-AB. The proportion of 2C ceils increased while cells with higher DNA ploidy declined in the roots of treated plants, resulting in an enlarged root meristematic zone. The expression level of PARP2 was very low in the meristematic zone but high in the maturation zone, consistent with a role of PARP in inhibiting mitosis and promoting cell differentiation. Our results suggest that PARPs play an important role in root development by negatively regulating root cell division.