Roles of APETALA2/Ethylene-Response Factors in Regulation of Fruit Quality

AbstractCrop yield loss due to flooding is a threat to food security. Submergence-induced hypoxia in plants results in stabilisation of group VII ETHYLENE RESPONSE FACTORS (ERF-VIIs), which aid survival under these adverse conditions. ERF-VII stability is controlled by the N-end rule pathway, which proposes that ERF-VII N-terminal cysteine oxidation in normoxia enables arginylation followed by proteasomal degradation. The PLANT CYSTEINE OXIDASEs (PCOs) have been identified as catalysts of this oxidation. ERF-VII stabilisation in hypoxia presumably arises from reduced PCO activity. We directly demonstrate that PCO dioxygenase activity produces Cys-sulfinic acid at the N-terminus of an ERF-VII peptide, which then undergoes efficient arginylation by an arginyl transferase (ATE1). This is the first molecular evidence showing N-terminal Cys-sulfinic acid formation and arginylation by N-end rule pathway components, and the first ATE1 substrate in plants. The PCOs and ATE1 may be viable intervention targets to stabilise N-end rule substrates, including ERF-VIIs to enhance submergence tolerance in agronomy.

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Respons molekuler Hevea brasiliensis ethylene response factors (HbERFs) sebagai marka ekspresi gen terhadap stimulasi ethephon pada klon-klon tanaman karet Moleculer response of Hevea brasiliensis ethylene response factors (HbERFs) as expression marker genes in response to ethephon stimulation in rubber tree clones

E-Journal Menara Perkebunan ◽

10.22302/ppbbi.jur.mp.v82i2.22 ◽

2016 ◽

Vol 82 (2) ◽

Author(s):

Riza Arief PUTRANTO ◽

. KUSWANHADI ◽

Pascal MONTORO

Keyword(s):

Gene Expression ◽

Real Time ◽

Hevea Brasiliensis ◽

Gene Expression Analysis ◽

Rubber Tree ◽

Rt Pcr ◽

Response Factors ◽

Ethylene Response ◽

Ethylene Response Factors ◽

Expression Marker

Abstract Real-Time quantitative RT-PCR technique is a sensitive method for measuring the accumulation of gene transcripts. This widely used technique in a variety of plant species; including rubber tree (Hevea brasiliensis) must meet basic criteria in order to produce accurate gene expression markers. Gene expression markers associated to the response of ethephon stimulation such as the Hevea brasiliensis Ethylene Response Factors (HbERFs) family has been characterized in a single rubber clone. It is known that the effect of genotype on rubber tree clones can give different expression of the same gene. This difference can be converted into a profile that characterizes clones to a certain trait. This study aimed to identify gene expression profile in response to ethephon stimulation using six HbERFs (HbORA47, HbRAP2.3, HbERF12, HbERF3, HbABR1, HbRRTF1) in three rubber tree clones having contrasted latex metabolism (PB 260, SP 217, and RRIM 600). Total RNA was isolated from 18 samples and used for cDNA synthesis. The quality of cDNAs was examined by PCR using HbActin primer. HbRH2b was selected among the 11 housekeeping genes to be used as an internal control in gene expression analysis. Gene expression analysis resulted to an induction and inhibition of HbERFs by ethephon stimulation which are specific to a particular clone. Expression profile of three Hevea clones showed distinct characteristics. The high latex metabolism clone PB 260 was characterized by the upregulated expression of HbRAP2.3 and HbERF12. The low latex metabolism clone SP 217 was characterized by the upregulated expression of HbRAP2.3 and HbRRTF1. Meanwhile, the profile of intermediate latex metabolism clone RRIM 600 was shown by downregulated expression of HbORA47 and up-regulated expression of HbABR1. This study shows that HbERFs gene family is an important expression marker because it can inform physiological conditions of rubber clones associated in response to ethephon. AbstrakTeknik Real-Time quantitative RT-PCR merupakan metode sensitif untuk mengukur akumulasi transkrip dari gen. Teknik yang telah banyak digunakan pada berbagai spesies tanaman, termasuk tanaman karet (Hevea brasiliensis) ini harus memenuhi kriteria dasar agar meng-hasilkan marka ekspresi gen yang akurat. Beberapa marka ekspresi gen terkait respons terhadap stimulasi ethephon seperti famili gen Hevea brasiliensis Ethylene Response Factors (HbERFs) telah dikarakterisasi pada satu klon tanaman karet. Sebagaimana diketahui, efek genotip pada klon tanaman karet dapat memberikan ekspresi yang berbeda dari gen yang sama. Perbedaan ekspresi tersebut dapat dikonversi menjadi sebuah profil yang menjadi karakteristik klon karet terhadap perlakuan tertentu. Penelitian ini bertujuan untuk mengidentifikasi profil ekspresi gen HbERFs pada tiga klon tanaman karet (PB 260, SP 217, dan RRIM 600) yang memiliki metabolisme lateks yang berbeda terhadap respons stimulasi ethephon dengan menggunakan enam gen HbERFs (HbORA47, HbRAP2.3, HbERF12, HbERF3, HbABR1, HbRRTF1). RNA total diisolasi dari 18 sampel dan digunakan untuk sintesis cDNA. Kualitas cDNA diperiksa dengan PCR menggunakan primer HbActin. Gen HbRH2b terseleksi diantara 11 gen housekeeping digunakan sebagai kontrol internal pada analisis ekspresi gen. Hasil dari analisis ekspresi gen menunjukkan bahwa stimulasi ethephon memiliki efek induksi dan inhibisi gen yang spesifik untuk klon tertentu. Profil ekspresi dari tiga klon tanaman karet yang diuji memperlihatkan perbedaan karakteristik. Klon metabolisme tinggi PB 260 ditunjukkan dengan ekspresi positif dari gen HbRAP2.3 dan HbERF12. Klon meta-bolisme rendah SP 217 ditunjukkan oleh ekspresi positif gen HbRAP2.3 dan HbRRTF1. Sedangkan klon metabo-lisme intermedier RRIM 600 memiliki profil ekspresi negatif dari HbORA47 dan ekspresi positif dari HbABR1. Penelitian ini memperlihatkan bahwa famili gen HbERFs merupakan marka ekspresi yang penting karena dapat menginformasikan kondisi fisiologis klon tanaman karet terkait respons terhadap ethephon.

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