Divergence and Redundancy in CSLD2 and CSLD3 Function During Arabidopsis Thaliana Root Hair and Female Gametophyte Development

Abstract

The Arabidopsis cellulose synthase-like D (CSLD) 2 and 3 genes are known to function in root hair development. Here, we show that these genes also play a role in female gametophyte development because csld2 csld3 double mutants were observed to have low seed set that could be traced to defects in female transmission efficiency. Cell biological studies of csld2 csld3 ovules showed synergid cell degeneration during megagametogenesis and reduced pollen tube penetration during fertilization. Although CSLD2 and CSLD3 function redundantly in female gametophyte development, detailed analyses of root hair phenotypes of progeny from genetic crosses between csld2 and csld3, suggest that CSLD3 might play a more prominent role than CSLD2 in root hair development. Phylogenetic and gene duplication studies of CSLD2 and CSLD3 homologs in Arabidopsis lyrata, Populus, Medicago, maize, and Physcomitrella were further performed to investigate the course of evolution for these genes. Our analyses indicate that the ancestor of land plants possibly contained two copies of CSLD genes, one of which developed into the CSLD5 lineage in flowering plants, and the other formed the CSLD1/2/3/4 clade. In addition, CSLD2 and CSLD3 likely originated from a recent genome-wide duplication event explaining their redundancy. Moreover, sliding-window dN/dS analysis showed that most of the coding regions of CSLD2 and CSLD3 have been under strong purifying selection pressure. However, the region that encodes the N-terminus of CSLD3 has been under relatively relaxed selection pressure as indicated by its high dN/dS value, suggesting that CSLD3 might have gained additional functions through more frequent non-synonymous sequence changes at the N-terminus, which could partly explain the more prominent role of CSLD3 during root hair development compared to CSLD2.

Transcriptional response ofArabidopsisseedlings during spaceflight reveals peroxidase and cell wall remodeling genes associated with root hair development

“…5). The ruptured root hairs of the prx44 and prx57 mutants were reminiscent of mutants for cellulose synthase‐like genes (Bernal et al, 2008; Galway et al, 2011; Park et al, 2011; Yoo et al, 2012a). This observation suggests that PRX44 and PRX57, like other class III peroxidases, are involved in redox‐dependent processes that modify the carbohydrate scaffold of the cell wall as the root hair extends.…”

DNL1, encodes cellulose synthase-like D4, is a major QTL for plant height and leaf width in rice (Oryza sativa L.)

“…AtCSLD2 and AtCSLD3 were considered as two closely related CSLD homologs in A. thaliana have redundant functions during both root hair and female gametophyte development [36]. It had proved that both AtCSLD1 and AtCSLD4 play important roles in pollen tube growth, and functionally redundant [26].…”

Intragenic Complementation ofCellulose Synthase-Like D1alleles in Root Hair Development

“…Thus far, mutations in CSLD5 have been associated with defects in stem growth (Bernal et al, 2007), in CSLD1 and CSLD4 with pollen tube development (Bernal et al, 2008; Wang et al, 2011), and in CSLD2 and CSLD3 with defective root hairs (Favery et al, 2001; Wang et al, 2001; Bernal et al, 2008; Galway et al, 2011). Yoo et al (Yoo et al, 2012) also showed that plants lacking both CSLD2 and CSLD3 had defects in female gametophyte development.…”