Overexpression of a serine carboxypeptidase increases carpel number and seed production in Arabidopsis thaliana

Abstract

Seed production is an ultimate component of crop yield. Increasing seed production has long been a pursuit for crop breeders and is an indisputable measure of food safety. Advances in biotechnology can provide novel means to achieve increased seed production by genetic engineering. Overexpression of ECS1 (Extra Carpels and Seeds), a gene encoding a serine carboxypeptidase, partially suppresses the leaf phenotypes of mutant bri1‐5, a weak allele of brassinosteroid‐insensitive 1 (BRI1). Moreover, overexpression of ECS1 increases the number of carpels and seeds per fruit (silique) in Arabidopsis thaliana. Most of the ECS1‐overexpressing lines have three‐carpel siliques instead of two‐carpel siliques found in wild type, while some even have four‐carpel siliques. Wild‐type plants have an average seed number of 66.2 ± 3.6 per silique, whereas ECS1‐overexpressing lines contain 88.1 ± 4.1 seeds per silique. The total seed weight per silique increases by about 33% in ECS1‐overexpressing plants due to the increased total number of seeds. In addition, ECS1 overexpression enhances the multi‐carpel phenotypes in clavata3‐2 and causes severely fasciated stems in det2 mutants. To the best of our knowledge, it has not been previously shown that overexpressions of genes that encode serine carboxypeptidases are implicated in reproductive development or produce an increased carpel and seed numbers in any plant species.

Characterization of BRS1 Functions in Plant Stress Responses

“…However, we saw no visible phenotypes with the BRS1 knockdown mutant, brs1-1 ( Fig. 1), consistent to no significant phenotype was observed in BRS1 mutant [4][5][6][7].…”

“…Its overexpression can rescue the receptor mutant of brassinosteroid (BR), bri1-5, indicating BRS1 might play an important role in BR signaling [4,5]. BRS1 has five close homologs, of which three can suppress bri1-5 developmental defects [6]. In contrast, no significant phenotypes have been identified in single or double mutants of either BRS1 or its homologs [4,6,7].…”

“…BRS1 has five close homologs, of which three can suppress bri1-5 developmental defects [6]. In contrast, no significant phenotypes have been identified in single or double mutants of either BRS1 or its homologs [4,6,7]. This suggests that BRS1 and its homologs are functionally redundant in Arabidopsis, making difficulties to clarify the precise roles of BRS1.…”

Genome‐wide identification, classification and expression analysis of the serine carboxypeptidase‐like protein family in poplar

“…These suggested SCPL proteins might work in biochemical pathways and be vital for normal plant growth and development, for the synthesis of compounds that protect plants against pathogens and ultraviolet rays, and for resistance to natural and manmade xenobiotics (Milkowski and Strack ). ECS1 (Extra Carpels and Seeds) over‐expressing Arabidopsis showed sensitivity to BR too (Wen et al ). The Sad7 gene could also resist soil‐borne pathogens, so as to better protect plants.…”

“…Li et al () suggested that SCP46 was a master regulator of grain filling and seed germination, possibly via participating in the ABA signaling, and the GS5 gene played a positive role in regulating grain size (Li et al ). The thousand‐grain weight of the ECS1 over‐expressing plant seed increased by about 33% compared with the wild‐type (Wen et al ). Additionally, NtSCP1 and NtSCP2 controlled the cell elongation (Bienert et al ).…”