RESUMO
Multiple C2 domain and transmembrane region proteins (MCTPs) are a group of evolutionarily conserved proteins and show emerging roles in mediating protein trafficking and signaling transduction. Although, several studies showed that MCTPs play important roles during plant growth and development, their biological functions in cotton remain largely unknown. Here, we identify and characterize 33 GhMCTP genes from upland cotton (Gossypium hirsutum) and reveal the diverse expression patterns of GhMCTPs in various tissues. We also find that GhMCTP7, GhMCTP12, and GhMCTP17 are highly expressed in the main stem apex, suggesting their possible roles in shoot development. Through analyzing different cotton species, we discover plant heights are closely related to the expression levels of GhMCTP7, GhMCTP12, and GhMCTP17. Furthermore, we silence the expression of GhMCTP genes using virus-induced gene silencing (VIGS) system in cotton and find that GhMCTP7, GhMCTP12, and GhMCTP17 play an essential role in shoot meristem development. GhMCTPs interact with GhKNAT1 and GhKNAT2 and regulate meristem development through integrating multiple signal pathways. Taken together, our results demonstrate functional redundancy of GhMCTPs in cotton shoot meristem development and provide a valuable resource to further study various functions of GhMCTPs in plant growth and development.
RESUMO
The objective of this study is to test stem apex sizes in the in vitro establishing of Angelonia integerrima in order to obtain explants without by fungi and bacteria contamination for further multiplications. The treatments consisted of different stem apex sizes (1.0, 3.0, 5.0, 7.0, 9.0 and 11.0 mm). At 45 and 90 days of cultivation, a count of contaminated explants and a count of shoots per explant formed were performed. In a second experiment, explants were cultivated in a medium containing different concentrations of benzylaminopurine (BAP) (0.0, 0.05, 0.10, 0.15 and 0.20 mg L-1). After 56 days of cultivation, the following variables were evaluated: shoot length, shoot fresh mass and number of shoots. During the explant establishment phase (45 days), only stem apexes with 1.0 mm in size were not contaminated. However, in the second subculture (at 90 days), only shoots from initial explants, with 7 mm in size or larger, were contaminated. Regarding multiplication, the presence of BAP showed a positive linear behavior for all variables. It is possible to obtain A. integerrima seedlings free of contamination in vitro by fungi and bacteria, using initial explants less than or equal to 5 mm. IBA provided a linear increment for the multiplication of this species.
O objetivo do trabalho foi testar tamanhos de ápices caulinares no estabelecimento in vitro de Angelonia integerrima, a fim de obter explantes sem contaminações por fungos e bactérias para posterior multiplicação. Os tratamentos consistiram de tamanhos de ápices caulinares: 1,0; 3,0; 5,0; 7,0; 9,0 e 11,0 mm. Após 45 e 90 dias de cultivo foi realizada a contagem de explantes contaminados e o número de brotos formados por explante. Em um segundo experimento, explantes foram cultivados em meio contendo diferentes concentrações de benzilaminopurina (BAP): 0,0; 0,05; 0,10; 0,15 e 0,20 mg L-1. Após 56 dias de cultivo foram avaliados: comprimento e massa fresca da parte aérea e número de brotos. Durante a fase de estabelecimento (45 dias), somente explantes com 1,0 mm não apresentaram contaminação, já no segundo subcultivo (aos 90 dias) somente brotações oriundas de explantes com tamanho inicial igual ou superior a 7 mm apresentaram contaminação. Com relação à multiplicação, a presença de BAP apresentou comportamento linear positivo para todas as variáveis analisadas. É possível obter mudas de A. integerrima livres de contaminações in vitro por fungos e bactérias, utilizando explantes iniciais menores ou iguais a 5 mm. O BAP proporcionou incremento linear para a multiplicação da espécie.
