Ectopic expression of a Brassica rapa AINTEGUMENTA gene (BrANT-1) increases organ size and stomatal density in Arabidopsis

Abstract

The AINTEGUMENTA-like (AIL) family plays a central role in regulating the growth and development of organs in many plants. However, little is known about the characteristics and functions of the AIL family in Chinese cabbage (Brassica rapa L. ssp. pekinensis). In this study, a genome-wide analysis was performed to identify the members of the AIL family in Chinese cabbage. We identified three ANT genes and six ANT-like genes of Chinese cabbage, most of which were differentially expressed in different organs or tissues. Furthermore, compared with the wild-type line, the size of different organs in the 35S-BrANT-1 line was significantly increased by promoting cell proliferation. Meanwhile, over-expression of BrANT-1 also increases the stomatal number and delays the leaf senescence. Transcriptome analyses revealed that a set of cell proliferation and stoma development genes were up-regulated, while the senescence-associated genes were down-regulated, suggesting these genes may be involved in BrANT-1 regulated processes for controlling organ size, stomatal density and leaf senescence. In summary, this study offers important insights into the characteristics and functions of the ANT genes in Chinese cabbage, and provides a promising strategy to improve yield or head size in Chinese cabbage breeding programs.

Genetic regulators of leaf size in Brassica crops

“…In A. thaliana, ANT overexpression resulted in large leaves due to increased cell proliferation, indicating that ANT promotes leaf growth by regulating cell division 16 . In Chinese cabbage, three ANT and six ANT-LIKE (BrAIL) genes have been identified, and the expression of the BrANT genes and three of the BrAIL genes was responsive to auxin treatment 17 . Among these homologs, BrANT-1 shows the highest protein sequence similarity to the A. thaliana ANT protein (AtANT).…”

“…The expression of STOMAGEN was also significantly enhanced in the transgenic plants. Thus, BrANT-1 may also regulate stomatal density by upregulating the STO-MAGEN gene 17 .…”

“…1). First, auxin promotes leaf growth by inducing BrARGOS and BrANT to accelerate cell proliferation and repressing BrARP1 and BrDRM1 to enhance cell expansion 17,20,26 . Meanwhile, ethylene restricts cell expansion and leaf growth through BrERF4 by downregulating EXP genes 33,34 .…”

Genome-wide identification AINTEGUMENTA-like (AIL) genes in Brassica species and expression patterns during reproductive development in Brassica napus L.

“…To investigate the sequences of the conserved AP2 domains in A. thaliana and the Brassica species, a multiple sequence alignment was performed using the 107 AIL proteins identified [4,6,22]. These two AP2 domain regions were highly conserved in the AIL proteins.…”

“…Among them, the AIL genes comprise an APETALA 2 (AP2) subfamily known to be involved in growth-related processes in a variety of plants [3,4,[15][16][17][18]. These genes play an important role in regulating the growth and development of organs (e.g., embryos and flowers) [1,3,[19][20][21][22]; for example, loss-of-function mutations in ANT resulted in A. thaliana with smaller organs [18,21,23], while overexpression of the ANT genes caused increases in organ size [1,24,25]. In addition, some AIL genes were shown to be involved in the differentiation of embryogenic stem cells from somatic cells in A. thaliana [26][27][28], oil palm (Elaeis guineensis) [29], and coconut (Cocos nucifera) [30,31].…”