Expression Pattern Analysis Of Arabidopsis RLK301-RLK439 In Embryo And Preliminary Study Of A Mutant Affecting Male And Female Gametophyte Development

Receptor-like kinases(RLKs)form a major gene family,including at least 610 members in Arabidopsis.A typical RLK protein contains a protein kinase catalytic domain(KD),a transmembrane domain(TM)and an extracellular ligand-binding domain(ED).RLKs play important roles in mediating cellular responses to various environmental cues and are involved in many biological processes,including plant growth and development,adaptability to environment and defense responses.Embryo development of Arabidopsis begins with the formation of zygote until the end of seed formation.In this process,the zygote divides in order to produce 8-cell proembryo,16-cell proembryo,globular embryo,heart-shaped embryo,torpedo embryo and cotyledon embryo.It is known that there are only 8 RLKs that play critical biological functions during embryo development,while whether other RLK genes also regulate this process is not elucidated.To systematically study their roles in regulating plant embryo development,GUS reporter lines driven by 135 RLK promoters were used to analyze their expression patterns in different organs,such as fruit pods,seeds,floral organ abscission zones,andembryos at different stages.Our results showed that 31 out of 135 RLK genes express in the embryo and RLK410?RLK429 are expressed in protodermis.Three RLK genes,RLK301-RLK303,are expressed in the embryo with similar patterns to SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE 1(SERK1).Results of yeast two-hybrid and BiFC analyses indicated that these three RLKs interact with SERKs,and they can also form dimers.These results provide a valuble reference for studying the biological functions of theseimportant RLKs during embryo development.To reveal the biological functions of RLK358,a T-DNA insertion line of this gene was obtained from ABRC.Phenotypic analyses indicated that the homozygous mutant does not show any obvious phenotype.However,the seed setting rate of its heterozygous mutant is significantly reduced and the pod length was shorter.Microscopic observations of mature pollen and ovules found that the male and female gametophytes of heterozygous rlk358 mutant are abnormal.Crossing analysis showed that the abortion phenotype is caused by defective female gametophytes.Further genetic experiments revealed that the defects are not caused by the lesion in RLK358 and the mutation that lead to these defect s are still under further analysis.