Variation in the expression of a transmembrane protein influences cell growth in Arabidopsis thaliana petals by altering auxin responses

Abstract

Background The same species of plant can exhibit very diverse sizes and shapes of organs that are genetically determined. Characterising genetic variation underlying this morphological diversity is an important objective in evolutionary studies and it also helps identify the functions of genes influencing plant growth and development. Extensive screens of mutagenised Arabidopsis populations have identified multiple genes and mechanisms affecting organ size and shape, but relatively few studies have exploited the rich diversity of natural populations to identify genes involved in growth control. Results We screened a relatively well characterised collection of Arabidopsis thaliana accessions for variation in petal size. Association analyses identified sequence and gene expression variation on chromosome 4 that made a substantial contribution to differences in petal area. Variation in the expression of a previously uncharacterised gene At4g16850 (named as KSK) had a substantial role on variation in organ size by influencing cell size. Over-expression of KSK led to larger petals with larger cells and promoted the formation of stamenoid features. The expression of auxin-responsive genes known to limit cell growth was reduced in response to KSK over-expression. ANT expression was also reduced in KSK over-expression lines, consistent with altered floral identities. Auxin responses were reduced in KSK over-expressing cells, consistent with changes in auxin-responsive gene expression. KSK may therefore influence auxin responses during petal development. Conclusions Understanding how genetic variation influences plant growth is important for both evolutionary and mechanistic studies. We used natural populations of Arabidopsis thaliana to identify sequence variation in a promoter region of Arabidopsis accessions that mediated differences in the expression of a previously uncharacterised membrane protein. This variation contributed to altered auxin responses and cell size during petal growth.

Transcriptional dissection of petty spurge (Euphorbia peplusL.) reproductive structures supports theEuphorbiacyathium as an inflorescence rather than a complete flower

“…The young staminate flowers had multiple significant GO terms associated with stamen and pollen development but did not have significant ATP or NADPH related terms. The mature pistillate flowers had two GO terms associated with petal development; the pistillate flower-enriched gene causing this significant GO hit, Ep_chr1_g00250, is in an orthogroup with arabidopsis AT4G16850, KronbladStorleK (KSK; the name is Swedish for petal size) which influences auxin responses during petal development (Miller et al, 2020). Compared with the mature pistillate flower, the younger pistillate flower was enriched for more GO terms relating to reproductive structure development, suggesting that the patterning of the pistillate flower is more active in this earlier stage.…”